Seasonal Development of Ice Algae Near Chesterfield Inlet, N.W.T., Canada

Abstract
Ice algal chlorophyll a, (Chl), an estimator of biomass, was measured throughout the growing season (March–May) near Chesterfield Inlet on the northwest coast of Hudson Bay (63°30′N). The log10 transformation of Chl per square metre was a negative linear function of snow depth at any given date and location. Maximum biomass reached about 170 mg Chl∙m−2 over deep water but only one tenth as much over shallow water. This smaller standing crop was correlated with lower concentrations of nitrate in shallow water, postulated to result from nitrogen uptake by kelp. Ice-associated amphipods were abundant but had little detectable effect on the development of ice algal biomass. Ice algal Chl over deep water was predicted closely by the model developed for Resolute at 75°N, relating Chl to overlying snow depth and cumulative surface light. It appears that, where nutrients are adequate, ice algal biomass below first-year sea ice can be predicted for much of the Arctic from two variables, cumulative surface light and snow depth.